Book excerpt: Physics of laser crystals has been constantly developing since the invention of the laser in 1960. Nowadays, more than 1500 wide-band-gap and semiconductors crystals are suitable for the production of the laser effect. Different laser devices are widely used in science, medicine and communication systems according to the progress achieved in the development of laser crystal physics. Scintillators for radiation detection also gained benefit from these developments. Most of the optically active materials offer laser radiations within the 500 to 3000 nm region with various quantum efficiency which fit the usual applications. However, new crystals for laser emissions are needed either in the blue, UV and VUV - region or far IR- region, especially for medicine, computer microchip production and for undiscovered practical uses. Scientific problems of the growth and properties of laser crystals are discussed in numerous books and scientific journals by many scientists working in the field. Therefore, we thought that joint discussions of the scientific and technical problems in laser physics will be useful for further developments in this area. We have proposed to held a Workshop on Physics of Laser Crystals for attempting to induce additional advances especially in solid state spectroscopy. This NATO Advanced Research Workshop (ARW) was hold in Kharkiv • Stary Saltov th nd (Ukraine) on august 26 - September 2 , 2002, and was mainly devoted to the consideration 0 f modem approaches and Iast results in physics of laser crystals.